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Adding reverse post order
1 parent 243245a commit c9629cb

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Lines changed: 344 additions & 130 deletions

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‎graphs-core/src/main/java/com/github/moaxcp/graphs/PropertyGraph.java‎

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@@ -971,6 +971,49 @@ default Stream<Vertex<ID>> breadthFirstStream(ID... start) {
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return StreamSupport.stream(Spliterators.spliteratorUnknownSize(iterator, Spliterator.ORDERED), false);
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}
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/**
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* Returns a reverse-post-order {@link Iterator} of every {@link Vertex} in this graph. This is a reverse of a
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* postOrderIterator starting at the provided vertices.
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* @throws NullPointerException if start is null or any id in start
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* @throws IllegalArgumentException if start contains ids that are not in the graph
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* @param start ids of traversal
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* @return
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*/
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default Iterator<Vertex<ID>> reversePostOrderIterator(ID... start) {
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var iterator = postOrderIterator(start);
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var list = new LinkedList<Vertex<ID>>();
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while(iterator.hasNext()) {
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list.addFirst(iterator.next());
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}
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return new Iterator<Vertex<ID>>() {
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@Override
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public boolean hasNext() {
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return list.size() != 0;
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}
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@Override
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public Vertex<ID> next() {
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if(list.size() == 0) {
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throw new NoSuchElementException("Could not find next element.");
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}
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return list.removeFirst();
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}
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};
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}
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/**
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* Returns a reverse-post-order {@link Stream} of every {@link Vertex} in this graph. This is a reverse of a
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* postOrderIterator starting at the provided vertices.
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* @throws NullPointerException if start is null or any id in start
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* @throws IllegalArgumentException if start contains ids that are not in the graph
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* @param start ids of traversal
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* @return
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*/
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default Stream<Vertex<ID>> reversePostOrderStream(ID... start) {
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var iterator = reversePostOrderIterator(start);
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return StreamSupport.stream(Spliterators.spliteratorUnknownSize(iterator, Spliterator.ORDERED), false);
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}
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/**
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* Returns true if this graph is empty.
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* @return

‎graphs-manual/src/docs/asciidoc/index.adoc‎

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@@ -345,6 +345,24 @@ include::{sourcedir}/com/github/moaxcp/graphs/manual/PostorderTraversal.java[tag
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image::images/postOrderTraversal.gif[post order]
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== reverse-post-order iterator and post-order stream
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An iterator and stream are provided to perform reverse-post-order depth first traversal.
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.reversePostOrderIterator()
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[source,java,indent=0]
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----
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include::{sourcedir}/com/github/moaxcp/graphs/manual/ReversePostorderTraversal.java[tags=reversePostOrderIterator]
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----
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.reversePostOrderStream()
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[source,java,indent=0]
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----
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include::{sourcedir}/com/github/moaxcp/graphs/manual/ReversePostorderTraversal.java[tags=reversePostOrderStream]
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----
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image::images/reversePostOrderTraversal.gif[reverse post order]
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== breadth first iterator and breadth first stream
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An iterator and stream are provided to perform breadth first traversals.
@@ -365,6 +383,10 @@ image::images/breadthFirstTraversal.gif[post order]
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== Releases
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== 0.16.0-SNAPSHOT
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Adding reversePostOrder iterator and stream.
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== 0.15.0
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Adding new project `graphs-guava` and `graphs-graphviz-guava-gif`.

‎graphs-manual/src/test/java/com/github/moaxcp/graphs/manual/ReversePostorderTraversal.java‎

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@@ -0,0 +1,59 @@
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package com.github.moaxcp.graphs.manual;
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import com.github.moaxcp.graphs.DirectedPropertyGraph;
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import com.github.moaxcp.graphs.PropertyGraph.Vertex;
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import com.github.moaxcp.graphs.graphviz.greenrobotgif.GreenrobotGifSubscriber;
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import com.github.moaxcp.graphs.greenrobot.DirectedEventPropertyGraph;
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import java.nio.file.Path;
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import java.util.Iterator;
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import org.greenrobot.eventbus.EventBus;
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import org.junit.jupiter.api.Test;
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public class ReversePostorderTraversal {
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@Test
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void reversePostOrderTraversal() {
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var bus = new EventBus();
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var graph = new DirectedEventPropertyGraph<String>(bus);
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graph.edge("A", "B")
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.edge("B", "C")
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.edge("B", "D")
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.edge("D", "E")
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.edge("D", "C")
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.edge("A", "D")
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.edge("D", "A")
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.edge("A", "E")
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.edge("F", "G")
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.edge("G", "D");
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var gif = new GreenrobotGifSubscriber<>(graph, Path.of("src/docs/asciidoc/images/reversePostOrderTraversal.gif"));
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// tag::reversePostOrderIterator[]
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Iterator<Vertex<String>> iterator = graph.reversePostOrderIterator("A");
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while(iterator.hasNext()) {
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Vertex<String> vertex = iterator.next();
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vertex.property("color", "green");
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}
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// end::reversePostOrderIterator[]
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gif.writeFile();
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}
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@Test
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void postOrderStream() {
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var graph = new DirectedPropertyGraph<String>();
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graph.edge("A", "B")
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.edge("B", "C")
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.edge("B", "D")
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.edge("D", "E")
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.edge("D", "C")
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.edge("A", "D")
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.edge("D", "A")
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.edge("A", "E")
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.edge("F", "G")
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.edge("G", "D");
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// tag::reversePostOrderStream[]
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graph.reversePostOrderStream("A").forEach(v -> v.property("color", "green"));
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// end::reversePostOrderStream[]
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}
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}

‎graphs-test/src/test/java/publicapi/PostOrderDepthFirstIteratorTest.java‎

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@@ -1,19 +1,17 @@
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package publicapi;
22

3-
import com.github.moaxcp.graphs.*;
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import com.github.moaxcp.graphs.PropertyGraph.*;
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import com.github.moaxcp.graphs.testframework.*;
6-
import org.junit.jupiter.api.*;
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import org.junit.jupiter.params.*;
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import org.junit.jupiter.params.provider.*;
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import java.util.*;
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import static com.github.moaxcp.graphs.testframework.MethodSources.*;
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import static com.github.moaxcp.graphs.testframework.PathOrder.*;
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import static com.google.common.truth.Truth.*;
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import static java.util.stream.Collectors.*;
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import static org.junit.jupiter.api.Assertions.*;
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import com.github.moaxcp.graphs.PropertyGraph;
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import com.github.moaxcp.graphs.PropertyGraph.Vertex;
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import com.github.moaxcp.graphs.testframework.TestGraphs;
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import java.util.List;
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import java.util.NoSuchElementException;
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import org.junit.jupiter.api.DisplayName;
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import org.junit.jupiter.params.ParameterizedTest;
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import org.junit.jupiter.params.provider.MethodSource;
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import static com.google.common.truth.Truth.assertThat;
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import static java.util.stream.Collectors.toList;
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import static org.junit.jupiter.api.Assertions.assertThrows;
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public class PostOrderDepthFirstIteratorTest {
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@@ -98,18 +96,6 @@ void postOrderIterator(String name, PropertyGraph<String> graph, String[] start,
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}
9997
}
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101-
@TestDirectedGraphs
102-
void postOrderIteratorStart(PropertyGraph<String> graph) {
103-
complexTwoComponents(graph, POST_ORDER);
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var result = new ArrayList<String>();
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var iterator = graph.postOrderIterator("D", "G", "W");
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while(iterator.hasNext()) {
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result.add(iterator.next().getId());
108-
}
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assertThat(result).isEqualTo(List.of("E", "C", "B", "A", "D", "G", "W", "F", "Y", "Z", "X"));
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}
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@MethodSource("com.github.moaxcp.graphs.testframework.MethodSources#graphsPostOrder")
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@DisplayName("postOrderStream matches expected order")
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@ParameterizedTest(name = "{index} - {0} {2}")
@@ -120,14 +106,4 @@ void postOrderStream(String name, PropertyGraph<String> graph, String[] start, L
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assertThat(result).isEqualTo(expectedOrder);
122108
}
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124-
@TestDirectedGraphs
125-
void postOrderStreamStart(PropertyGraph<String> graph) {
126-
complexTwoComponents(graph, POST_ORDER);
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var result = graph.postOrderStream("D", "G", "W")
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.map(Vertex::getId)
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.collect(toList());
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assertThat(result).isEqualTo(List.of("E", "C", "B", "A", "D", "G", "W", "F", "Y", "Z", "X"));
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}
133109
}

‎graphs-test/src/test/java/publicapi/ReversePostOrderDepthFirstIteratorTest.java‎

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package publicapi;
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import com.github.moaxcp.graphs.PropertyGraph;
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import com.github.moaxcp.graphs.PropertyGraph.Vertex;
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import com.github.moaxcp.graphs.testframework.TestGraphs;
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import java.util.List;
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import java.util.NoSuchElementException;
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import org.junit.jupiter.api.DisplayName;
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import org.junit.jupiter.params.ParameterizedTest;
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import org.junit.jupiter.params.provider.MethodSource;
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import static com.google.common.truth.Truth.assertThat;
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import static java.util.stream.Collectors.toList;
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import static org.junit.jupiter.api.Assertions.assertThrows;
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public class ReversePostOrderDepthFirstIteratorTest {
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@TestGraphs
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void nullStart(PropertyGraph<String> graph) {
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var exception = assertThrows(NullPointerException.class, () -> graph.reversePostOrderIterator((String[]) null));
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assertThat(exception).hasMessageThat().isEqualTo("start is marked non-null but is null");
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}
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@TestGraphs
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void nullInOther(PropertyGraph<String> graph) {
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graph.vertex("A").vertex("B");
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var exception = assertThrows(NullPointerException.class, () -> graph.reversePostOrderIterator("A", null, "B"));
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assertThat(exception).hasMessageThat().isEqualTo("\"id\" in \"start\" must not be null.");
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}
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@TestGraphs
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void startNotInGraph(PropertyGraph<String> graph) {
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var exception = assertThrows(IllegalArgumentException.class, () -> graph.reversePostOrderIterator("A"));
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assertThat(exception).hasMessageThat().isEqualTo("vertex \"A\" not found in graph.");
35+
}
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@TestGraphs
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void hasNext_EmptyGraph(PropertyGraph<String> graph) {
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var iterator = graph.reversePostOrderIterator();
40+
assertThat(iterator.hasNext()).isFalse();
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}
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43+
@TestGraphs
44+
void next_EmptyGraph(PropertyGraph<String> graph) {
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var iterator = graph.reversePostOrderIterator();
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var exception = assertThrows(NoSuchElementException.class, () -> iterator.next());
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assertThat(exception).hasMessageThat().isEqualTo("Could not find next element.");
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}
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@TestGraphs
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void hasNext_beforeIteration(PropertyGraph<String> graph) {
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graph.vertex("A");
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var iterator = graph.reversePostOrderIterator();
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assertThat(iterator.hasNext()).isTrue();
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}
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@TestGraphs
58+
void hasNext_MultipleBeforeIteration(PropertyGraph<String> graph) {
59+
graph.vertex("A");
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var iterator = graph.reversePostOrderIterator();
61+
assertThat(iterator.hasNext()).isTrue();
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assertThat(iterator.hasNext()).isTrue();
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assertThat(iterator.hasNext()).isTrue();
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assertThat(iterator.next().getId()).isEqualTo("A");
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}
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67+
@TestGraphs
68+
void hasNext_MultipleBetweenComponents(PropertyGraph<String> graph) {
69+
graph.vertex("A");
70+
graph.vertex("B");
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var iterator = graph.reversePostOrderIterator();
72+
assertThat(iterator.hasNext()).isTrue();
73+
assertThat(iterator.next().getId()).isEqualTo("B");
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assertThat(iterator.hasNext()).isTrue();
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assertThat(iterator.hasNext()).isTrue();
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assertThat(iterator.hasNext()).isTrue();
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assertThat(iterator.next().getId()).isEqualTo("A");
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}
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@TestGraphs
81+
void next_withoutCallingHasNext(PropertyGraph<String> graph) {
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graph.vertex("A");
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var iterator = graph.reversePostOrderIterator();
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assertThat(iterator.next().getId()).isEqualTo("A");
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assertThat(iterator.hasNext()).isFalse();
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}
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@MethodSource("com.github.moaxcp.graphs.testframework.MethodSources#graphsReversePostOrder")
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@DisplayName("reversePostOrderIterator matches expected order")
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@ParameterizedTest(name = "{index} - {0} {2}")
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void reversePostOrderIterator(String name, PropertyGraph<String> graph, String[] start, List<String> expectedOrder) {
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var iterator = graph.reversePostOrderIterator(start);
93+
for(String expected : expectedOrder) {
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String result = iterator.next().getId();
95+
assertThat(result).isEqualTo(expected);
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}
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}
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@MethodSource("com.github.moaxcp.graphs.testframework.MethodSources#graphsReversePostOrder")
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@DisplayName("reversePostOrderStream matches expected order")
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@ParameterizedTest(name = "{index} - {0} {2}")
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void reversePostOrderStream(String name, PropertyGraph<String> graph, String[] start, List<String> expectedOrder) {
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var result = graph.reversePostOrderStream(start)
104+
.map(Vertex::getId)
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.collect(toList());
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assertThat(result).isEqualTo(expectedOrder);
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}
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}

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